A paint system is applied to a commercial aircraft prior to customer delivery. The paint system may include a decorative coating, which enhances the aircraft's appearance, provides operator markings, etc. The paint system may also include a protective coating in certain areas to prevent corrosion. On composite aircraft, the protective coating also prevents ultra violet radiation, erosion, and moisture ingress.
The paint system may include a primer, which is applied to an exterior surface of the fuselage. In addition to covering composite skin, the primer covers fasteners. One or more coats of paint is applied over the primer.
“Halos” sometimes appear around countersunk fasteners. The halos appear as visible circular or semi-circular depressions in the paint around the fasteners. These halos are undesirable, as they detract from the aircraft's appearance.